Highway crossing protection control apparatus



INVENTOR. Ralph 11. lfemmerel' BY u) L first.

HIS ATTORNEY R R KEMMERER 2,838,656

HIGHWAY CROSSING PROTECTION CONTROL APPARATUS Filed Feb. 11, 1954 June 10, 1958 United States Patent HIGHWAY CROSSING PROTECTION CONTROL APPARATUS Ralph R. Kemmerer, Swissvale, Pa., assignor to Westinghouse Air Brake Company, Wilmerding, Pa, a corporation of Pennsylvania My invention relates to highway crossing protection control apparatus and particularly to highway crossing protection control apparatus for use in non-signaled territory on single track railways over which traffic may move in both directions.

It is often necessary for the safety of highway traffic to provide warning signals at the intersection of a highway and a stretch of railway track. Such warning signals are usually controlled by track relays associated with insulated track sections in approach to the intersection and by a track relay associated with the section including the highway-railway intersection. It is obvious that the apparatus which controls these warning signals must o erate in a safe manner so that highway trafi-lc will be fully protected from possible collision with approaching trains. a

One possible cause of failure in such apparatus is the failure of a track circuit associated with one of the approach track sections. This failure or fault condition can be due to a broken rail or to an open circuit resulting from the disconnection of leads-running from. the track battery or track relay. to the track rails. In signaled territory,

such a failure will not cause a hazardous condition because if a track circuit fails, the associated signal will display its stop aspect. Accordingly, any train approaching that signal will come to a stop. However, if the stretch of track is not provided with a signaling system, no indication of a track circuit failure will be given and it is possible for a train to then approach the crossing One object of my invention is to provide highway crossing protection control apparatus which will operate to provide substantially normal operation in the event that one of the approach track circuits fails due to one of the enumerated fault conditions. i

Another object of my invention is to provide highway crossing protection control apparatus at the intersection of a highway and a stretch of railway track over which tratfic may move in either direction which apparatus will operate in a substantially normal manner in the eventthat either one or both of the approach track circuitssho uld fail.

A further object of my invention is to provide in high-v way crossing protection control apparatus means for shifting the control of the apparatus from the track relayassociated with an approach section to a track instrument 2,838,656 Patented June 10, 1958 located at the entrance end of the approach section in the event that the associated track circuit should fail.

Yet another object of my invention is to provide in highway crossing protection control apparatus means for preventing the energization of one of the directional stick relays in the event that the crossing section track relay should become shunted for some reason other than the presence of a train or vehicle in the crossing section.

According to a preferred embodiment of my invention, I provide first, second'and third track sections in a stretch of track over which trafiic may move in both directions. The track sections are so located that trafiic may move through them in the order named or in the reverse order. A highway intersects the second track section. Adjacent the intersection is a highway crossing signal. Each of the track sections is provided with the usual track circuit including a track relay. I further provide a first track instrument located in the vicinity of the end of the first track section remote from the intersection and a second track instrument located in the vicinity of the end of the third section remote from the intersection. I also provide a slow release repeater relay' for the track relay associated with the second section. In addition, first and second control stick relays associated with the first and third sections are provided. The first and second control stick relays are normally controlled by the track relays associated with the first and third sections, respectively, but the control of the control stick relays will be shifted to the associated track instrument in the event that the associated track circuit fails. Regardless of how the control stick relays are controlled, they will function in a manner similar to approach section track relays in conventional highway crossing protection control apparatus; that is, they will be normally energized but will be dc? energized when a train occupies the associated track section. The control stick relays control the crossing signal so that the signal will operate while a train is approaching the crossing. I also provide first and second normally deenergized directional stick relays which are associated with the first and third sections, respectively. Each directional stick relay is energized by a circuit including a back contact of its related control stick relay, a front contact of the opposing directional stick relay, a back contact of the second track relay' and a front contact of the slow release repeater relay. By employing such an energizing circuit, the possibility of either directional stick relay becoming falsely energized because of the shunting of the second track relay by a steel treaded tractor .or similar vehicle is eliminated. Accordingly, each directional stick relay will only become energized by a train or vehicle entering the second section from the first or third section and moving in such a direction that it will recede through the section associated with the directional stick relay to be energized. The directional stick relay will thereafter remain energized until the train or vehicle clears its associated section to prevent the operation of the crossing signal while a train or vehicle is receding from the crossing through the associated section.

Other objects of my invention will become. clear here-, inafter as the characteristic features of construction and mode of operation of my novel highway crossing protection control apparatus are described in detail.

The accompanying drawing is a diagrammatic view of highway crossing protection control apparatus embodying my invention.

Referring now to the drawing, a stretch of railway track made up of the track rails 1 and 2 is intersected by a. highway H. Located adjacent the intersection are two highway crossing signals X81 and X82 which are connected in multiple and controlled over a back contact of a highway crossing signal control relay XR. The crossing signals may be of any of a-nurnber of suitable U types such as flashing light signals or gates or, as here shown, electric bells.

The track rails are provided with insulated joints 3 in order to form two approach track sections WT and ET and a crossing track section XT. Each of the track sec tions is provided with a track circuit including a track battery and a track relay designated respectively by the reference characters B and R prefixed with the reference character of the associated track section. The end of each track section ET and WT which is remote from the intersection is located from the intersection a sulficient distance so that when a train enters either track section, the crossing signal operation will be initiated to provide a minimum safe warning time prior to the train reaching the crossing. For instance, if the maximum speed for the stretch is 80 miles per hour or 117 feet per second, and the minimum safe warning time is assumed to be 20 seconds, the remote ends of sections ET and WT will be located 2340 (117 X 20) feet from the crossing.

Located adjacent the end of section WT remote from highway H is a track instrument WTZ, and located adjacent the end of section ET remote from highway H is a track instrument ETZ. These track instruments may be of any of several well known types such as microphones or photo-electric devices or they may be treadle actuated track instruments such as that shown and described in Letters Patent of the United States No. 2,588,798, granted on March 11, 1952, to Herbert L. Home et al. for Buffer Means. Each track instrument has a normally closed contact a which becomes open when the wheels of a train engage the track instrument.

Associated with sections WT and ET, respectively, are control stick relays WXASR and EXASR. Under normal conditions each of the control stick relays is partially controlled by its associated track relay but when its associated track circuit fails each control stick relay will then be partially controlled by its associated track instrument in a manner to be made clear presently.

A slow acting repeater relay XTPR is provided which relay is essentially a front contact repeater of relay XTR. It is the provision of the slow acting relay XTPR and circuits associated therewith that enables my novel apparatus to accomplish the function of preventing failure of the apparatus in the event that the crossing section is shunted by a steel treaded tractor or the like. 7

Associated with the control stick relays are time element relays WTER and ETER and time element stick relays WTESR and ETESR. These relays function to shift the control of the control stick relays from the track relays to the track instruments upon failure of the track 5 circuits in a manner which will become clear as the description proceeds. Time element relays WTER and ETER may be of any of a number of conventional types having normally open front contacts a and b which be come closed after the time element relay has been energized for a predetermined time interval; a normally closed back contact 0 which becomes open after the time element relay has been energized for a predetermined time interval; and a checking contact d here shown as a back contact with a circle at the fixed point of the contact. The checking contact is arranged so that it will become open immediately upon the time element relay becoming energized.

I also'provide two directional stick relays WXSR and EXSR associated with sections WT and XT, respectively, and which are energized when a train recedes through the associated track section in order to prevent the operation of the crossing signals while a train is receding from the crossing.

The energy for all the apparatus other than the track relays may be supplied by anysuitable source, such for example, as a battery LB having a positive terminal B and a negative terminal N.

' The apparatus is shown in the drawing in its normal condition with the stretch of track unoccupied. Accordingly, the track relays WTR, XTR and ETR are all energized. With relay XTR energized, an obvious circuit for supplying energy to relay XTPR including from contact a of relay XTR is closed, so that this relay is also energized.

Furthermore, relay WXASR is energized over a circuit passing from positive terminal B of battery LB, over front contact a of relay WTR, back contact c of relay WTESR, front contact b of relay XTPR in multiple with back contact c of relay WXSR, front contact b of relay WTR and the winding of relay WXASR to negative terminal N of battery LB. With relay WXASR picked up, a stick circuit for relay WXASR is established which is the same as its energizing circuit except that it includes front contact b of relay WXASR instead of front contact b of relay WTR. The last traced circuits both include a back contact of relay WTESR. The reasons for relay WTESR being released at this time will become clear as this description proceeds. With relay WTESR released, contact a of track instrument WTZ is not included in any closed circuit and, for reasons which will become clear, as long as the track circuit associated with section WT does not fail, this condition will persist. Accordingly, with the track circuit associated with section WT functioning properly, the operation of the track instrument WTZ will not have any effect on the remainder of the apparatus.

A circuit is also established for supplying energy to relay EXASR, the circuit passing from positive terminal B of battery LB, over front contact a of relay ETR, back contact 0 of relay ETESR, front contact 0 of relay XTPR in multiple with back contact (I of relay EXSR, front contact b of relay ETR and the winding of relay EXASR to negative terminal N of battery LB. With relay EXASR picked up, a stick circuit for that relay which is the same as its energizing circuit except that it includes front contact b of relay EXASR instead of front contact a of relay ETR is also established. It will be seen that the energizing and stick circuits for relay EXASR both include back contact 0 of relay ETESR. The reason for relay ETESR being released will become clear presently. .With relay ETESR released, contact a of track instrument ETZ is not included in any closed circuit and, for reasons which will become clear, as long as the track circuit associated with section ET does not fail, this condition will persist. Accordingly, with the track circuit associated with section ET functioning properly the operation of track instrument ETZ will not have any effect on the remainder of the apparatus.

As shown, relay's WXSR and EXSR are both released because their energizing circuits, which will be traced subsequently, are open at several points.

With the relays in the condition described, a first or normal circuit is established for energizing relay XR passing from positive terminal B of battery LB, over front contact d of relay EXASR, checking contact d of relay ETER, front contact 2 of relay XTPR, checking contact d of relay WTER, front contact d of relay WXASR and the winding of relay XR to negative terminal N of battery LB. With relay XR energized the obvious energizing circuit for crossing signals XSl and X82 is open at back contact a of relay XR and, accordingly, the crossing signals XSl and XSZ are deenergized. The last traced energizing circuit for relay XR includes a checking contact of each of the time element relays ETER and WTER. The reasons for these relays being deenergized at this time will become clear as this description proceeds.

I will now assume that a train enters the stretch from the left and travels through the stretch from left to right as viewed in the drawing. When the train enters section WT track instrument WTZ will be actuated but this will have no effect upon the remainder of the apapratus. Furthermore, upon the train entering section WT, track relay WTR will be shunted and will release, thereby opening the previously traced energizing and stick circuits for relay WXASR to cause that relay to release; Upon the release of relay WXASR the previously traced first energizing circuit for relay XR will become open at front contact d of relay WXASR and relay XR will release to close the energizing circuit for crossing signals XS1 and X82. Accordingly, the crossing signals will commence operating. Upon the release of relay WTR, a first circuit will be established for energizing relay WTER which circuit may be traced from positive terminal B of battery LB, over back contact a of relay WTR, back contact a of relay WTESR and the winding of relay WTER to negative terminal N of battery LB. Accordingly, relay WTER will commence timing and will open its checking contact d. Let it be assumed that the predetermined time interval necessary for relay WTER to close its front contacts and to open its back contact is longer than the longest time it will take any train to traverse section WT. Accordingly, for reasons which will become clear, the timing action of relay WTER will have no effect on the apparatus at this time.

When the train enters section XT it will shunt relay XTR and cause that relay to release thereby deenergizing relay XTPR. However, relay XTPR will not immediately release due to its slow release characteristic. With relay WXASR released,'relay EXASR energized, relay XT PR picked up and relay XTR released, an energizing circuit will be established for relay EXSR passing from-positive terminal B of battery LB, over back contact c of relay WXASR, back contact of relay WTER, back contact b of relay XTR, front contact d of relay XT PR, back contact c of relay ETER, front contact 0 of relay EXASR, back contact d of relay WXSR and the winding of relay EXSR to negative terminal N of battery LB. Accordingly, relay EXSR will pick up. After relay EXSR picks up, relay XTPR will release to thereby open the energizing circuit for relay EXSR. However, a first stick circuit for relay EXSR will now be established which may be traced from positive terminal B of battery LB, over back contact a of relay XTPR in multiple with back contact a of relay XTR, front contact b of relay EXSR and the winding of relay EXSR to negative terminal N of battery LB. Accordingly, at this time, relay EXSR will be maintained in its energized condition by its first stick circuit.

With relay XTPR released and relay EXSR picked up, the previously traced energizing and stick circuits for relay EXASR will be open and, accordingly, relay EXASR will release. The release of relay EXASR will open the previously traced first energizing circuit for relay XR at an additional point. Furthermore upon the release of relay EXASR, a second stick circuit for relay EXSR will be established passing from positive terminal B of battery LB, over back contact c of relay EXASR, back contact c of relay ETER, front contact a of relay EXSR and the winding of relay EXSR to negative terminal N of battery LB. 1

Upon the train vacating section WT, relay WTR will pick up thereby reenergizing relay WXASR over its previously traced energizing circuit passing from positive terminal B of battery LB, over front contact a of relay WTR, back contact 0 of relay WTESR, back contact c of relay WXSR, front contact b of relay WTR and the winding of relay WXASR to negative terminal N of battery LB. Accordingly, relay WXASR will pick up and establish its previously traced stick circuit whch is identical with the energizing circuit just traced except that it includes front contact b of relay WXASR instead of front 6 and relay WTER will become deenergized to thereby release its checking contact d.

When the train enters section ET relay ETR will become deenergized and it will release thereby opening the energizing circuit for relay EXASR at an additional point. Accordingly, relay EXASRwill remain deenergized as long as the train occupies section ET and therefore, relay EXSR will remain energized as long as the train occupies section ET. Furthermore, upon the release of relay ETR, an energizing circuit for relay ETER will become established which circuit may be traced from positive terminal B of battery LB, over back contact a of relay ETR, back contact a of relay ETESR and the winding of relay ETER to negative terminal N of battery LB. Accordingly, relay ETER will commence timing and will open its checking contact at to thereby open the previously traced normal or first energizing circuit for relay XR at an additional point. Let it'be assumed that the time interval it-takes relay ETER to open its back contact 0 and close its front contacts a and b is longer than the time it will take the slowest train to traverse section ET. Accordingly, for reasons which will be made clear as the description proceeds, the timing operation of relay ETER will have no effect on the remainder of the apparatus at this time.

Upon the train vacating section XT, relay XTR will pick up to reestablish the energizing circuit for relay XTPR which will also pick up after a brief time interval due to its slow pickup characteristic. With relays XT PR and XTR picked up, the previously traced first stick circuit for relay EXSR will become open but relay EXSR will now remain energized by its second stick circuit. With relay XTPR now picked up a second energizing circuit will be established for relay XR which circuit may be traced from positive terminal B of battery LB, over front contact e of relay EXSR, front contact 2 of relay XTPR, checking contact d of relay WTER, front contact d of relay WXASR and the winding of relay XR to negative terminal N of battery LB. Accordingly, relay XR will pick up and deenergize crossing signals XS1 and X52.

When the train vacates section ET relay ETR will pick up and close the previously traced energizing circuit for relay EXASR passing from positive terminal B of battery LB, over front contact a of relay ET R, back contact c of relay ETESR, front contact c of relay XTPR, front contact b of relay ETR, and the winding of relay EXASR to negative terminal N of battery LB. Accordingly, relay EXASR will pick up and reestablish its previously traced stick circuit which is the same as its energizing circuit except that it includes front contact b of relay EXASR instead of front contact 12 of relay ETER. With relay EXASR energized, the second stick circuit for relay EXSR will become open at back contact 0 of relay EXASR and, accordingly, relay EXSR will release. However, relay XR will now remain energized over its first or normal energizing circuit. In this manner the apparatus is restored to its normal condition.

It will be obvious that due to the symmetry of the apparatus, the operation of the apparatus with all the track circuits operating properly and a train moving through the stretch from right to left will be substantially the same as the previously described operation of the apparatus with the train moving through the stretch from left to right. Accordingly, it is deemed unnecessary to describe the operation of the apparatus with a train moving through the stretch from right to left.

In prior art systems for highway crossing warning signals, the warning signal on a two direction running stretch of track could be disabled if one of the track circuits developed a fault condition. For example, let us assume a normal train movement from left to right on the drawing in a system which is not provided with an auxiliary gircuit controlled by the timing relay ETER and track instrument In the course of inormal operationldirectional stick relay EXSR would become .energizedand would eliminate control stick relay EXASR and consequently track relay ETR from the control of the crossing signal. Now, if the track circuit for track relay ETR should be disabled whilethe directional stick relay is energized so that relay ETR could not be reenergized, the directional stick relay would remain energized after the train vacates the receding section ET Therefore, a train approaching the highway crossing from the right, as viewed in the the drawing, would fail to start operation of the warning signal. Protection against such failure is provided by relays WTER andETER and track instruments WTZ and ETZ.

I will now assume that the track circuit associated with section WT becomes open circuited for some reason such as a broken rail. Accordingly, relay WTR will release and open the energizing and stick circuits for relay WXASR. Therefore, the crossing signal will commence operating. Furthermore, with relay WTR released relay WTER will become energized over its previously traced first energizing circuit and will commence timing. Checking contact d of relay WTER will immediately become open thereby opening the previously traced first energizing circuit for relay XR at an additional point. After the expiration of its predetermined time interval, relay WTER will close its front contacts a and b and will open its back contact c. Upon the closing of front contact a of relay 'WTER, a circuitwill be established for energizing relay WTESR whichcircuit may be traced from positive terminal B of battery LB, over back contact a of relay WTR, front contact a of relay WTER and the Winding of relay WTESR to negative terminal N of battery LB. Therefore, relay WTESR will pick up and establish a stick circuit passing from positive terminal B of battery LB, over back contact a of relay WTR, front contact a of relay WTESR and the winding of relay WTESR to negative terminal N of the battery LB. Therefore, relay WTESR will remain picked up. With relay WTESR picked up and stuck up the previously traced energizing circuit for relay WTER will become open at back contact a of relay WTESR but relay WTER will now be energized over a second energizing circuit which may be traced from positive terminal B of battery LB, over back contact. a of relay WXASR, front contact b of relay WTESR and the winding of relay WTER to negative terminal N of the battery LB.

Upon relay WTESR picking up, a second energizing circuit will be established for relay WXASR passing from positive terminal B of battery LB, over front contact a of track instrument WTZ, frontcontact 0 of relay WTESR, front contact b of relay XTPR in multiple with back contact 0 of relay WXSR, front contact b of relay WTER and the winding of relay 'WXASR to negative terminal N of battery LB. Accordingly, relay WXASR will pick up'and establish a second stick circuit for relay WXASR which is the same as its second energizing circuit except that it includes front contact b of relay WXASR instead of front contact b of relay WTER. Accordingly, relay'WXA-SR will remain picked up and will open the previously traced second energizing circuit for relay WTER thereby causing the relays front contacts a and b to open and its back contact c and its checking contact d to close. Therefore, the previously traced first or normal energizing circuit for relay XR will become reestablished and relay XR will pick up to deenergize crossing signals XS! and X82. It will be seen, therefore, that failure of the track circuit associated with section WT will cause time element relay WTER and relay WTESR to operate to transfer the control of relay WXASR from track relay WTR to track instrument WTZ. However, if for some reason a circuit through track instrument WTZ for energizing relay WXASR is not completed, their the 75 8 crossing signals will continue to operate indicating that a track circuit failure has occurred.

It will beobvious from the symmetry of the apparatus that if the track circuit associated with section ET becer'ncs open, relay ETR will release. Relay ETER will become energized a'ndafter a predetermined time interval it will pick up to energize relay ETESR which will in turn pick :up andestablish an energizing circuit for relay EXASR including front contact .a of track instrument ET Upon relay EXASR picking up, relay ETEn will become deenergized and will release. Accordingly, failure of the track circuit associated with section ET will cause relays ETER and ETESR to operate to transfer the control of relay EXASR from track relay ETR to track instrument ETZ. I

Assuming that the track circuit associated with section W1" has failed and relays WTER and WTESR have operated so that relay WXASR is now controlled in part by track instrument WTZ, I will now assume that a train moves through the stretch from left to right. When the train enters section WT track instrument WTZ will become actuated thus causing front contact a of the track instrument WTZ to open, thereby opening the previously traced second stick circuit for relay WXASR. There fore, relay WXASR will release. Accordingly, the first or normal energizing circuit for relay XR will become open at front contact d of the relay WXASR and relay XR willrelease to energize crossing signals and X52. Furthermore, with relay WXASR now released relay WTER will become energized over its previously traced second energizing circuit and will commence timing, thereby opening its checking contact (1. However, the time which it will take relay WTER to close its front contacts and open its back contact is longer than the long' est time a train will take to transverse section WT and, accordingly, the timing action is of no importance at this time.

When the train clears track instrument WTZ the track instrument WTZ will become restored to its normal condition but relay WXASR will now remain deenergized because its previously traced second energizing circuit including front contact b of relay WTER is open at that point and its previously traced second stick circuit including front contact [2 of relay WXASR is open at that point. Accordingly, the crossing signals X51 and X82 will continue to operate.

When the train enters section XT relay XTR will release and will deenergize relay XTPR which will remain picked up due to its slow release characteristic. Accordingly, the previously traced energizing circuit for relay EXSR will become established and relay EXSR will pick up. After relay EXSR is picked up relay XTPR will release thereby opening the energizing circuit for relay EXSR. However, the previously traced first stick circuit for relay EXSR will now be closed and relay EXSR will remain energized. The release of relay XTrR will open the energizing circuit for relay XR at an additional point and the circuit will remain open as long as relay XTPR remains released. Accordingly, signals X51 and X82 will continue to operate as long as the train occu pies section XT.

Furthermore, upon the release of relay XTBR a third energizing circuit for relay WXASR will become established passing from positive terminal B of battery LB, over front contact a of track instrument WTZ, front contact 0 of relay WTESR, back contact 6 of relay WXSR, back contact b of relay XTPR and the winding of relay WXASR to negative terminal N of battery LE3. Accordingly, relay WXASR will pick up and establish a stick circuit which is identical with the energizing circuit just traced except it includes front contact I) of relay WXASR instead of back contact I) of relay XTPR. it will be seen, therefore, that relay WXASR will now be energized independently ofrelay XTPR.

Furthermore, upon the release of relay XTPR the previously traced energizing and stick circuits for relay EXASR will become open since relays XTPR and EXSR are released and picked up, respectively. Therefore, relay EXASR will release. Upon the release of relay EXASR the previously traced second stick circuit for relay EXSR will become established.

When the train enters section ET, relay ETR will release to thereby open the energizing and stick circuits for relay EXASR at an additional point. 'It will be seen therefore that as long as the train occupies section ET, relay EXSR will remain energized over its second stick circuit. Furthermore, upon the release of relay ETR, the previously traced energizing circuit for relay ETER will become established and relay ETER will commence timing. Therefore, its checking contact (I will become open but this will have no effect on the apparatus. As was stated earlier, the time it will take relay ETER to close its front contacts a and b and open its back contact c is longer than the longest time it will take a train to traverse section ET and accordingly, the timing action of relay ETER has no effect on the remainder of the apparatus at this time. 1

When the train clears section XT relay XTR will pick up and energize relay XTPR which will pick up after a brief time interval. With relay XTPR picked up the previously trace-d second energizing circuit for relay XR including front contact e of relay EXSR will become established and relay XR will pick up thereby deenergizing crossing signals X51 and X52.

Upon the train vacating section ET relay ETR will pick up thereby establishing the previously traced energizing circuit for relay EXASR which will pick up. Upon relay EXASR picking up the previously traced second stick circuit for relay EXSR will become open and relay EXSR will release thereby opening the previously traced second energizing circuit for relay XR. However, relay XR will now be energized over its previously traced first or normal energizing circuit. In this manner the apparatus will be restored to its initial condition. It will be seen, therefore, that in the event that the track circuit associated with section WT fails and control of relay WXASR is shifted to track instrument WTZ, the apparatus will function in a manner substantially the same as when the track circuit is working.

Withthe track circuit associated with section WT being open circuited for a sufiiciently long time to transfer the control of relay WXASR from track relay WTR to track instrument WTZ, I will now assume that a train enters the stretch from the right and moves through the stretch from right to left' When the train enters section ET it will actuate track instrument ETZ but this will have no effect upon the apparatus. Furthermore, upon the train entering section ET track relay ETR will become shunted and will release to thereby deenergize relay EXASR.

With relay EXASR released the first or normal energizing circuit for relay XR will become open at front contact d of relay EXASR and, accordingly, relay XR will release to thereby energize crossing signals X81 and X82. Furthermore, upon the release of relay EXASR relay ETER will becomecnergized by its previously traced first energizing circuit. Accordingly, relay ETER will commence its timing operation and open its checking contact d, but the timing operation of relay ETER has no effect on the operation of the apparatus at this time.

When the train enters section XT it will shunt relay XTR causing that relay to release. Relay XTPR will be deenergized but it will not immediately release due to its slow release characteristic. Therefore, an energizing circuit will be established for relay WXSR passing from positive terminal B of battery LB, over back contact c of relay EXASR, back contact c of relay ETER, front contact d of relay XTPR, back contact b of relay XTR, back contact c of relay WTER, front contact c of relay WXASR, back contact c of relay EXSR and the winding of relay WXSR to negative terminal N of battery LB. Accordingly, relay WXSR will pick up. After relay WXSR picks up relay XTPR will release to open the energizing circuit for relay WXSR but a first stick circuit for relay WXSR will now be closed passing from positive terminal B of battery LB, over back contact a of relay XTPR in multiple with back contact a of relay XTR, from contact b of relay WXSR and the winding of relay WXSR to negative terminal N of battery LB. Accordingly, relay WXSR will remain picked up.

With relay WXSR picked up and relay XTPR released the previously traced second stick circuit for relay WXASR will become open and relay WXASR will release. With relay WXASR released the previously traced second en ergizing circuit for relay WTER will become closed and relay WTER will commence its timing action. Accordingly, checking contact d of relay WTER will become open. The opening of checking contact d of relay WTER will have no effect upon the operation of the apparatus since the circuit in which it is included is already open at several other points.

When the train vacates section ET, relay ETR will pick up and establish the previously traced first energizing circuit for relay EXASR passing from positive terminal B of battery LB, over front contact a of relay ETR, back contact 0 of relay ETESR, back contact d of relay EXSR, front contact b of relay ETR and the winding of relay EXASR to negative terminal N of battery LB. Accordingly, relay EXASR will pick up and establish a stick circuit which is identical with the last traced energizing circuit except that it includes front contact b of relay EXASR instead of front contact b of relay ETR.

When the train vacates section XT relay XTR will pick up and reenergize relay XTPR which will pick up after a short delay due to its slow pickup characteristic. Accordingly, the first stick circuit for relay WXSR will become open but relay WXSR will now remain picked up over its second stick circuit. It will be noted that relay WXASR will'remain released and relay WTER will remain energized as previously described.

When the train actuates track instrument WTZ the front contact a of track instrument WTZ will become open but this will have no effect upon the apparatus because the circuit including front contact a of track instrument WTZ is open at several other points. After the train clears track instrument WT Z relay WTER will conclude its timing action and will close its front contacts a and b and'open its back contact 0. Accordingly, the second stick circuit for relay WXSR will become open and relay WXSR will release. Furthermore, with front contact b of relay WTER now closed the previously traced second energizing circuit for relay WXASR passing from positive terminal B of battery LB, over front contact a of track instrument WTZ, front contact 0 of relay WTESR, front contact b of relay XTPR in multiple with back contact 0 of relay WXSR, front contact b of relay WTER and the winding of relay WXASR to negative terminal N of battery LB will become established. Accordingly, relay WXASR will pick up and establish its previously traced second stick circuit which is identical with the energizing circuit just traced except that it includes front contact b of relay WXASR instead of front contact b of relay WT ER. Upon the picking up of relay WXASR the previously traced second energizing circuit for relay WTER will become open and relay WTER will become deenergized thereby opening its front contacts a and b and closing its back contact 0 and its checking contact d. It will be seen therefore that the first or normal energizing circuit for relay XR will become reestablished and relay XR will remain energized. In this manner the apparatus will be restored to its initial condition. Accordingly, it will be seen that when the track circuit associated with section WT fails and the control of relay WXASR shifted to track instrument WTZ, the apparatus will function in a manner substantially similar to the normal manner when a train moves through the stretch from right to left.

it will be obvious from the symmetry of the apparatus that if the track'circuit associated with section ET fails and control of relay EXASR is transferred from track relay ETR to track instrument ETZ, the apparatus will function in a manner substantially similar to the operation of the apparatus when the track circuit associated with section WT fails. It will also be obvious from an inspection of the drawing that if both approach track circuits fail thereby transferring .control of both control stick relays from their assaciated track relays to their associated track instruments that the apparatus will function in a manner similar to that already described.

My highway crossing protection control apparatus also includes novel means for preventing the energization of the directional stick relays in the event that the crossing section XT should be falsely shunted such as by a steel treaded tractor. Referring to the drawing let it be assumed that a tractor moving along highway H'crosses the rails in section XT thereby shunting relay XTR and causing that relay to release. Upon relay XTR releasing it will deenergize relay XTPR which after a short time interval will also release. I Will now assume that a train enters section WT thereby shunting relay WTR and causing that relay to release and deenergize relay WXASR. If the train should now back out of section WT, relays WTR and WXASR would be reenergized and the system would return to its normal condition. In the past, under these conditions, it was possible for relay EXSR to become energized so that a train entering section ET and proceeding toward the crossing would fail to start the crossing signals. However, it will be seen that with my novel energizing circuit for the directional stick relays, this condition cannot arise since the energizing circuit for relay EXSR will now be open at front contact d of relay XTPR. Accordingly, relay EXSR will remain deenergized.

Another feature of the system lies in its ability to prevent energization of the Wrong directional stick relay in the event that a train stops in an approach section. Assume that a train stops in section WT long enough for relay WTER to close its delayed pick-up contacts and complete an energizing circuit for relay WXASR. Then when a train enters section XT there will be no pick-up circuit for relay EXSR and the crossing signal will continue to operate while the train recedes through section ET. With relay WXASR energized, a danger would exist that on the train entering section ET from section XT directional relay WXSR would pick up and on so doing would open the energizing circuit for relay WXASR so that relay WXSR would be stuck energized until relay WTER was again energized long enough to close the pick-up circuit for relay WXASR. This condition would prevent any trains approaching the crossing through section WT from starting the crossing signalsJ However, since a front contact of relay XTPR is in the energizing circuit for the direction stick relays, relay WXSR cannot be energized as described above because the particular contact of relay XTPR involved would drop away from its front point before a train traveling through section XT from section WT reached section ET. Thus, the system will operate normally under these circumstances.

It will be obvious from an inspection of the drawing that my novel means for preventing the false energization of directional stick relays will operate regardless of which track section is shunted by a train which subsequently backs off, and will also function in the same manner if the control of the control stick relays WXASR and EXASR has been transferred from the track relays to the associated track instruments.

Although, as was previously stated, my invention is particularly suitable for use in non-signaled territory, it will be obvious that it may be used to good advantage in 12 territory where a signaling system is' employed. Accordingly, nothing stated herein is intended to limit my invention to use in non-signaled territory.

Although I have herein shown and described only one form of highway crossing protection control apparatus embodying my invention, it will be understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

i. in combination with a stretch of track over which trafiic may move in one direction, said stretch being provided with a track section having a track circuit including a track relay, a track instrument adjacent the entrance end of said section,-time element means, means effective when said track relay is deenergized for energizing said time element means, a control relay, a first means effective only when said track relay is energized for energizing said control relay, a second means efiective only when said track instrument is in its normal condition and said time element means has been energized for a predetermined time interval for energizing said control relay, and signaling means controlled by said control relay.

2. In combination with a stretch of track over which tratfic may move in one direction, said stretch being provided with a track section having a track circuit includ ing a track relay, a track instrument in the vicinity of the entrance end of said section, a time element relay, a time element stick relay, means effective only when said track relay is deenergized for energizing said time element relay, means efiective only when said time element relay has been energized for a predetermined time in rval for energizing said time element stick relay, means effective when said track relay is deencrgized for maintaining said time element stick relay energized, a control relay, a first means effective only when said track relay is energized for energizing said control relay, a second means effective only when said track instrument is in its normal condition and said time element stick relay is energized for energizing said control relay, and signaling means controlled by said control relay.

3. In combination with a stretch of track over which trafiic may move in both directions, said stretch being provided with first, second and third track sections so situated that traflic may move through said sections in the order named or in the reverse order, each of said track sections being provided with a track circuit including a track relay, said second section being intersected by a highway, highway crossing protection control apparatus comprising a track instrument located in the vicinity of the end of said first section remote from the intersection, a control stick relay, a time element relay, a time element stick relay, first and second directional stick relays, a first means effective when the track relay asociated with said first section and said time element stick relay are deenergized for energizing said time element relay, a second means effective when said control stick relay is cleanergized and said time element stick relay is energized for energizing said time element relay, means effective when said first track relay is deenergized and said time element relay has been energized for a predetermined time intcrval for energizing said time element stick rclay, means effective when said first track relay is dcenergized for maintaining said time element stick relay energized; a first means eifective when said first track relay is error gized, said time element stick relay is deenergized and said first directional stick relay is dcenergized for energizing said control stick relay; a second means effective when said track instrument is in its normal condition, said time element stick relay is energized, said first directional stick relay is deenergized and the track relay associated with said second section is deenergized for energizing said control stick relay; a third means effective when said track instrument is in its normal condition, said time element stick relay is energized, said second track relay is energized 13 and said time element relay Has been energized for a predetermined time interval for energizing said control stick relay; means for inaintai ting said control stick relay energized efiective only when said track instrument is in its normal condition, said time element stick relay is energized and said second track relay is energized; means effective when a train approaching said intersection through said third section enters'said second section for energizing said first directional stick relay, means for maintaining said first directional stick relay energized efiective as long as said second or first sections are occupied, means.

efiective when a train approaching said intersection through said first section enters said second section for energizing said second directional stick relay, means for maintaining said second directional stick relay energized effective as long as said second or third sections are occupied; and a highway crossing signal adjacent said intersection and controlled by said control stick relay, said second and third track relays and said first and second directional stick relays.

4. In combination with a stretch of track over which traffic may move in both directions, said stretch being provided with first, second and third track sections so situated that trafiic may move through said sections in the order named or in the reverse order, each of said track sections being provided With a track circuit including a track relay,'said second section being intersected by a highway, highway crossing protection control apparatus comprising a track instrument located in the vicinity of the end of said first section remote from the intersection, a control stick relay, a time element relay, a time element stick relay, first and second directional stick relays, a first means including a back contact of the track relay associated with said first section and a back contact of said time element stick relay for energizing said time element relay, a second means including a back contact of said control stick relay and a front contact of said time element stick relay for energizing said time element relay, means including a back contact of said first track relay and a contact closed when said time element relay has been energized for a predetermined time interval for energizing said time element stick relay, a stick circuit for said time element stick relay including a back contact of said first track relay; a first means including a front contact of said first track relay, a back contact of said time element stick relay and a back contact of said first directional stick relay in multiple with a contact closed only when the track relayassociated with said second section is energized for energizing said control stick relay; a second means including a contact closed when said track instrument is in its normal condition, a front contact of said time element stick relay, a back contact of said first directional stick relay and a contact closed when said second track relay is deenergized for energizing said control stick relay; a third means including a contact closed when said track instrument is in its normal condition, a contact closed when said time element relay has been energized for a predetermined time interval, a front contact of said time element stick relay and a contact closed only when said second track relay is energized for energizing said control stick relay; a stick circuit for said control stick relay including a contact closed when said track instrument is in its normal condition, a front contact of said time element stick relay and a back contact of said first directional stick relay in multiple with a contact closed when said second track relay is energized; means effective when a train approaching said intersection through said third section enters said second section for energizing said first directional stick relay, means for maintaining said first directional stick relay energized efiective as long as said second or first sections are occupied, means effective when a train approaching said intersection through said second directional stick relay energized efiective as long as said second or third sections are occupied; and a highway crossing signal adjacent said intersection and controlled by said control stick relay, said second and third track relays and said first and second directional stick relays.

5. In combination with a stretch of track over which traffic may move in both directions, said stretch being provided with first, second and third track sections so situated that trafiic may move through said sections in the order named or in the reverse order, each of said track sections being provided with a track circuit including a track relay, said second section being intersected by a highway, highway crossing protection control apparatus comprising a first track instrument located'in the vicinity of the end of said first section remote from the intersection and a second track instrument located in the vicinity of the end of said third section remote from said intersection, first and second control stick relays, first and second time element relays, first and second time element stick relays, first and second directional stick relays, a first means including a back contact of the track relay associated with said first section and a back contact of said first time element stick relay for energizing said first time element relay, a second means including a back contact of said first control stick relay and a front contact of saidfirst time element stick relay for energizing said first time element relay, means including a back contact of said first track relay and a contact closed when said first time element relay has been energized for a predetermined time interval for energizing said first time element stick relay, a stick circuit for said first time element stick relay including a back contact of said first track relay; a. first means including a front contact of said first track relay, a back contact of said first time element stick relay and a back contact of said first directional stick relay in multiple with a contact closed when the track relay associated with said second section is energized for energizing said first control stick relay; a second means including a contact closed when said first track instrument is in its normal condition, a front contact of said first time element stick relay, a back contact of said first directional stick relay and a contact closed when said second track relay is deenergized for energizing said first control stick relay; a third means including a contact closed When said first track instrument is in its normal condition, a contact closed when said first time element relay has been energized for a predetermined time interval, a front contact of said first time element stick relay and a contact closed when said second track relay is energized for energizing said first control stick relay; a stick circuit for said first control stick relay including a contact closed when said first track instrument is in its normal condition, a front contact of said first time element stick relay and a back contact of said first directional stick relay in multiple with a contact closed when said second track relay is energized; a first means including a back contact of the track relay associated with said third section and a back contact of said second time element stick relay for energizing said second time element relay, a second means including a back contact of said second control stick relay and a front contact of said second time element stick relay for energizing said second time element relay, means including a back contact of said third track relay and a contact closed when said second time element relay has been energized for a predetermined time interval for energizing said second time element stick relay, a stick circuit -for said second time element stick relay including a back contact of said third track relay; a first means including a. front contact of said third track relay, a back contact of said second time element stick relay and a back contact of said second directional stick relay in multiple with a contact closed when said second track relay is energized for energizing said second control stick relay; a second means including a contact closed when said second track instrument is in its normal condition, a front contact of said second time element stick relay, a back contact of said second directional stick relay and a contact closed when said second track relay is deenergized for energizing said second control stick relay; a third means including a contact closed when said second track instrument is in its normal condition, a front contact of said second time element stick relay, a contact closed when said time element relay has been energized for a predetermined time interval and a contact closed when said second track relay is energized for energizing said second control stick relay; a stick circuit for said second control stick relay including a contact closed when said second track instrument is in its normal condition, a front contact of said second time ment stick relay and a back contact of said second directional stick relay in multiple with a contact closed when said second track relay is energized; means effective when a train approaching said intersection through said third section enters said second section for energizing said first directional stick relay, means for maintaining said first directional stick relay energized effective as long as said second or first section is occupied, means effective when a train approaching said intersection through said first section enters said second section for energizing said second directional stick relay, means for maintaining said second directional stick relay energized effective as long as said second or third section is occupied; and a highway crossing signal adjacent said intersection and controlled by said first and second control stick relays, said first and second directional stick relays and said second track relay.

6. In apparatus for controlling a highway crossing signal located adjacent the intersection of a highway and a stretch of track over which tralfic may move in both directions, said stretch being provided with first and second approach sections and a crossing section, said approach sections each having associated therewith means responsive to trafiic conditions therein for causing said signal to operate when a train approaches said intersection, said crossing section having a track circuit including a track relay having first and second conditions, the combination comprising first and second directional stick re lays for preventing the operation of the signal when a train recedes from the intersection, a slow acting repeater relay having first and second conditions and controlled by said track relay, means effective only when said t ack relay is in said second condition and said repeater relay is in said first condition for energizing said first di ectional stick relay, and means effective only Wii1 said track relay is in said second condition and said repeater relay is in said first condition for energizing said second directional stick relay.

7. In apparatus for controlling a highway crossing sig nal located adjacent the intersection of a highway a stretch of track over which trafiic may move in both directions, said stretch being provided with first and second approach sections and a crossing section, said approach sections each having associated therewith means respon sive to traffic conditions therein for causing said signal to operate when a train approaches said intersection, said crossing section having a track circuit including a track relay, the combination comprising first and second d ctional stick relays for preventing the operation of the signal wh n a train recedes from the intersection, a slow release repeater relay, means effective when said track relay is energized for energizing said repeater relay, means effective only when said track relay is deenergized and said repeater relay is picked up for energizing said first directional stick relay, and means effective only when said track relay is deenergized and said repeater relay is picked up for energizing said second directional stick relay.

8, In an apparatus for controlling a highway crossing signal located adjacent the intersection .of a highway and a stretch of track over which trafiic may move in both directions, said stretch b eing provided with a crossing section and first and second approach sections adjacent opposite ends of said crossing section, each of said approach sections having associated therewith means responsive to traffic conditions therein for causing said signal to operate when a train approaches said intersection, said crossing section having a track circuit including a track relay, the combination comprising first and second directional stick relays for preventing the operation of the signal when a train recedes from the intersection, a slow release repeater relay, means including a front contact of said track relay for energizing said repeater relay, means including a back contact of said track relay and a front contact of said repeater relay for energizing said first directional stick relay, and means including a back contact of said track relay and a front contact of said repeater relay for energizing said second directional stick relay.

9. In combination with a stretch of railway track over which trafiic may move in both directions, said stretch being provided with first, second and third track sections so situated that trafiic will move through the sections in the order named or in the reverse order, said second section being intersected by a highway, said second section being provided with a track circuit including a track relay; first and second control relays associated with said first and third sections, respectively, means for energizing said first control relay effective only when said first section is vacant, means for energizing said second control relay effective only when said third track section is vacant, the combination comprising a slow release repeater relay, means including a front contact of said second track relay for energizing said repeater relay; means including a back contact of said second control relay, a front contact of said repeater relay, a back contact of said second track relay and a front contact of said first control relay for energizing said first directional stick relay, means for maintaining said first directional stick relay energized effective as long as said second or first section is occupied; means including a back contact of said first control relay, a back contact of said second track relay, a front contact of said repeater relay and a front contact of said second control relay for energizing said second directional stick relay; and a highway crossing signal adjacent the intersection and controlled by said first and second control relays, said second track relay and said first and second directional stick relays.

l0. In'combination with a stretch of railway track over which tralfic may move in both directions, said stretch being provided with first, second and third track sections so situated that trafiic may move through said sections'in the order named or in the reverse order, each of said track sections being provided with a track circuit including a track 'relay, said second section being intersected by a highway, highway crossing protection control apparatus comprising a track instrument located in the vicinity of the end of said first section remote from the intersection, a second track instrument located in the vicinity of the end of said third section remote from said intersection, first and second control stick relays, first and second time element relays, first and second time element stick relays, first and second directional stick relays, a slow release repeater relay, a circuit for energizing said repeater relay including a front contact of the track relay associated with said second section, a first circuit including a back contact of said track relay associated with the first section and a back contact of said first time element stick relay for energizing said first time element relay, a second circuit including a hack contact of said first control stick relay and a front contact of said first time element stick relay for energizing said first time element relay, a circuit including a back contact of said first track relay and a contact closed when said first time element relay has been energized for a predetermined time interval for energizing said first time element stick relay, a stick circuit for said first time element relay including a back contact of said first track relay; a first circuit including a front contact of said first track relay, a back contact of said first time element stick relay and a back contact of said first directional relay in multiple with a front contact of said repeater relay for energizing said first control stick relay; a second circuit including a contact closed when said first track instrument is in its normal condition, a front contact of said first time element stick relay, a back contact of said first directional stick relay and a back contact of said repeater relay for energizing said first control stick relay; a third circuit including a contact closed when said first track instrument is in its normal condition, a front contact of said first time element stick relay, a contact closed when said first time element relay has been energized for a predetermined time interval and a front contact of said repeater relay for energizing said first control stick relay; a stick circuit for said first control stick relay including a contact closed when said first track instrument is in its normal condition, a front contact of said first time element stick relay and a back contact of said first directional stick relay in multiple with a front contact of said repeater relay; a first circuit including a back contact of said track relay associated with said third section and a back contact of said second time element stick relay for energizing said second time element relay, a second circuit including a back contact of said second control stick relay and a front contact of said second time element stick relay for energizing said second time element relay, a circuit including a back contact of said third track relay and a contact closed when said second time element relay has been energized for a predetermined time interval for energizing said second time element stick relay, a stick circuit for said second time element stick relay including a back contact of said third track relay; a first circuit including a frontcontact of said third track relay, a back contact of said second time element stick relay and a back contact of said second directional stick relay in multiple with a front contact of said repeater relay for energizing said 7 second control stick relay; a second circuit including a tact of said second time element stick relay, a contact closed when said second time relay has been energized for a predetermined time interval and a front contact of said repeater relay for energizing said second control stick relay; a stick circuit for said second control stick relay including a contact closed when said second track instrument is in its normal condition, a front contact of said second time element stick relay and a back contact of said second directional stick relay in multiple with a front contact of said repeater relay; a circuit including a back contact of said second control stick relay, a front contact of said repeater relay, a back contact of said second track relay, a front contact of said first control stick relay and a back contact of said second directional stick relay for energizing said first directional stick relay; a first stick circuit for said first directional stick relay including a back contact of said second track relay in multiple with a back contact of said repeater relay, a second stick circuit for said first directional stick relay including a back contact of said first control stick relay; a circuit including a back contact of said first control stick relay, a back contact of said second track relay, a front contact of said repeater relay, a front contact of said second control stick relay and a back contact of said first directional stick relay for energizing said second directional stick relay; a first stick circuit for said second directional stick relay including a back contact ofsaid second track relay in multiple with a back contact of said repeater relay, a second stick circuit for said second d1- rectional stick relay including a back contact of said second control stick relay; a signal control relay; a circuit including a front contact of said first control stick relay in multiple with a front contact of said first directional stick relay, a front contact of said repeater relay and a front contact of said second control stick relay in multiple with a front contact of said second directional stick relay for energizing said signal control relay; a highway crossing signal adjacent said intersection, and a circuit including a back contact of said signal control relay for energizing said highway crossing signal.

References Cited in the file of this patent UNITED STATES PATENTS 2,071,995 Allen Feb. 23, 1937 2,113,642 Dodd et al. Apr. 12, 1938 2,176,866 Allen Oct. 24, 1939 2,452,868 Quinlan NOV. 2,, 1948 2,740,887 Lower Apr. 3, 1956 

